Spring



May 10, 1949. P. G. GROOM 7 2,469,596

SPRING Filed Aug. 1, 1947 Patented May 10, 1949 UNITED STATES WXEENT OFFICE 2 Claims.

springs must do when a depression is formed in the upholstery, as when it is sat upon.

Under a heavy load these springs being necessarily highly limber are often compressed into a substantially fiat body, and particularly in Vehicle upholstery Where they assist in absorbing vertical motion this constant pancaking eventually breaks down the fibres, thus creating faults at some points at one of which the wire finally fractures.

A flaccid area in upholstery, or a permanent depression therein, are the manifestations of broken or weakened springs, and when such upholstery is presented for repair it is very noticeable that more often than not the person accustomed to sit in the lax portion of the upholstery is of more than normal weight. Obviously the springs must be constructed of light gauge wire and easily compressible so that proper resiliency is provided for underweight persons and juveniles.

The primary object of the invention is to provide an upholstery spring which will readily give and bend under the weight of a person of moderate heaviness, and also over a long period will withstand the burden and punishment inflicted by a person of extraordinary weight, by means of a novel structure which serves to preclude total collapse of the spring and which arrests the action of the spring only when it becomes for the most part compressed.

Another important object is to provide a cornbination of parts which embrace a conventional, or at least a common type of upholstery spring, so that no changeover is required in the manufacture of the metal portion of the spring.

Still another important object is to provide a new spring structure which Will be simple and inexpensive to produce and to purchase.

With the above and other objects in view as will be hereinafter apparent, the invention con-- sists in general of certain novel details of construction and combinations of parts hereinafter fully described, illustrated in the accompanying drawings and specifically claimed.

In the accompanying drawings like character of reference indicate like parts in the several Figure 3 is a side elevation showing the spring fully compressed.

In its present embodiment the invention consists broadly in combining a more or less conventional upholstery spring H] with a core l2 of spongy rubber or spongy rubber-like substance.

Usually these springs embrace the structure defined in a foregoing part of this specification. Preferably the core is square in section and extends the full height of the metal portion of the spring. Crosswise, the measurement between the diametrically opposed corners of the core is percepti bly greater than the diameter of the two or three reduced convolutions at the waist of the wire portion of the spring, and thus the core being dinted by these middle convolutions is held against longitudinal displacement while the spring is fully expanded.

As the spring is compressed the core contracts lengthwise with the wire portion and as it contracts it distends crosswise. Consequently, on compression the core at once begins to bulge first between the middle convolutions and finally between the end convolutions. This bulging does not retard the spring action at first, but when compression reaches the point where an extra heavy load would more or less completely flatten the wire portion of the spring were the core to be absent, the bulges intervening the convolutions arrest the progress of the spring toward pancaking and finally halt it when it still has considerable thickness. Thus the spring obviously is automatically adjustable to light and heavy loads without sacrifice of comfort to persons of the extremes in weight nor those ranked between.

There has thus been provided a simple and efiicient device of the kind described and for the purpose specified.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, therefore, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

I claim:

1. A compression spring comprising a spring wire structure consisting of a single length of wire formed to provide a pair of spirally wound ends, a plurality of normally, widely spaced helical coils centrally between said ends, said helical coils being of equal diameters, and. other helical coils between said central coils and ends being of gradually increasing diameters; in combination with a core of sponge rubber having a cross sectional area at its central portion as great as the area surrounded by the central portion of the spirally wound spring structure and having said central helical coils embracing the core to compress it on a helical line.

2. A compression spring comprising a spring wire structure consisting of a single length of Wire formed to provide a pair of spirally Wound ends, a plurality of normally widely spaced helical coils centrally between said ends, said helical coils being of equal diameters, and other helical coils between said central coils and ends being of gradually increasing diameters; in combination with a core of sponge rubber having a cross sectional area at its central portion as great as the area surrounded "by the central portion of the spirally wound spring structure and having said central helical coils embracing the REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Greene Dec. 14, 1926 Number 

